All Grown Up
by chocolatejazzf15
Summary: Phineas and Isabella finally confess their feelings, and end up together. They are madly in love, but, will they be able to cope with the responsibility, now that they're All Grown Up? Phinbella fluff, rated T for some language and scenes.
1. Ch 1 The Million Little Hints

** A/N Hey, welcome to my first-ish fic! Hope you enjoy and its not too cloudy for you, and, for copyright issues... Disclaimer: I do not own Phineas and Ferb, or any of the Canon characters. Happy Fictioning!**

**Chapter 1: The Million Little Hints**

**Phineas' POV**

We were all in the back yard when it happened. The moment that would change my life forever. It was just another regular, summer day, and me, Ferb, Baljeet, Buford and the Fireside Girls were hard at work on our latest invention. It was some sort of robot - the name escapes me - and it was truly magnificent, if I do say so myself. It was only until my catchphrase of 'Hey, where's Perry?' had sung through the air in its vocal glory, that I realised something was missing. "Hey, guys," I started. "Anyone seen Isabella today?" Everyone shook their heads, and Adyson spoke up, "Yeah, she wasn't even at the morning meeting today. Maybe she called off sick?" Silence sliced through the busy morning bustle, until my cell phone buzzed a catchy tune, making everyone jump at least two feet off the ground.

"I-I'll just be one moment." I stammered, running up to my room.

**Isabella's POV**

"Aaargh!" I yelled, face planting into my pillow. "Pick up, pick up, PICK UP! Jeez, Phineas, can't you realise ANYTHING!?" I began to sob slowly and rhythmically into the fluffy puff covering my face, staining the ivory sheet with tears. I was tired of his obliviousness, and just wanted him to get the hint. Just one. Just one of the million little hints. I, after minutes of mindlessly spilling out salty drops of water, felt myself slipping into the black oblivion of sleep. The relaxation washed over me, engulfing me with its protective darkness. Momentarily, a catchy text-tone rang through the air, a strong, familiar hand pulling me out of my trance. The message was from Phineas. It read:

** It's ok. Im coming over :-) xx**

A relaxed smile began to spread across my lips as the door creaked open. "Isabella?"

**Phineas' POV**

My eyes searched expectantly throughout the lower hall of the house, ready for her familiar catchphrase. Instead, I got ambushed by an ebony mass. It tackled me to the floor, slamming the door behind me as we fell. As it raised its head, I realised it wasn't an _it_, but completely the opposite. The black mass revealed a tear-stained, blue-eyed, sad-looking, Isabella. She began to sob deeply into my chest, murmuring three words. "I-I...love...y-you..." My body tensed as I processed it. Then, calming down, I reapised it was about time we exchanged thoughts. I gingerly kissed her hair, then lifted her off my chest. She looked alarmed, as if she thought I had rejected her. I held her there for what seemed like an eternity, tears welling up in my eyes. I pulled her towards me, smashing my lips into hers, my ginger stubble softly grazing her smooth chin.

"I...love you too..."

We just sat there, passionately cuddling and kissing for ages. An eternity. Our eternity.

* * *

**Author's POV**

The gang had been sitting, waiting in the Flynn-Fletcher backyard for hours, spamming Phineas and Isabella with 'What's going on?'s and 'Where are you?'s. Ferb, however, was sat underneath the infamous tree of their childhood, smirking in his all-knowing glory. Eventually, Linda emerged through the French doors, with her trademark plate of hot cookies. "Man," Buford chimed. "Look at what Phineas and Isabella are missing out on!" Despite being a good-natured comment, Mrs Flynn-Fletcher narrowed her eyes suspiciously.

"Why, exactly, are Phineas and Isabella missing out on anything, Buford?" Finally realising his mistake, Buford turned away, mumbling 'Oh, n-nothing...'. Linda then turned to Ferb expectantly. "Ferb?" He let out a sigh of relief, then, taking his step-mother's arm, started walking inside. "Well, you see, Phineas is older now, so he..."

* * *

**A/N**

**So, there you go! My first chapter! I know it's a little short, but for now that's what I'm going for. Hope it was sweet, and any reviews, negative or positive would be appreciated. Thanks for reading, hope you enjoy it! I will try to upload another chapter ASAP, but I am quite busy, so, you've been warned! Happy Fictioning!**

**Toots xx**


	2. Ch 2 A Brotherly Conflict

**Hey guys! Welcome to my second chapter! Just a quick shoutout, this chapter was inspired by the long-named, amazing idea-bearing, Yarthayaj'knaushtavdhladleklwa (if that isn't a mouthful, I don't know what is). I hope you enjoy, and as I said, reviews are much appreciated! Again...Disclaimer: I do not own Phineas and Ferb, or any of the Canon characters. Hope you enjoy and Happy Fictioning!**

**Chapter 2: A Brotherly Conflict**

**Ferb's POV**

Explaining to my step-mother in the gentlest, clearest way possible that Phineas and Isabella were (probably) together was, to say the least, difficult. She kept on interrupting, with statements like 'They're too young!' or 'Why didn't they run it past me first?'. By the time I had gotten the message across that no-one else but me knew about, well, _them_, it was nearly midnight. I was beginning to worry where Phin and Izzy were.

Ahh, never mind. I should probably leave them be. They were older now, despite the fact I was still Phineas' big bro. He never really liked to refer to himself as a 'younger brother', even though he got just as much leadership as he wished for. I was always quieter. I mean, I've come out of my shell a _lot _more in the last 8 years, but still. Just then Phin walked through the front door, a relieved but calm expression on his face. "Hey." He mumbled.

"Hey Phin. Where've you been? I had to explain to mum why you and Izzy were -"

"Why did you do that?"

"Do what?" I was getting confused now. First no vocal enthusiasm and now this? "Phin, are you just really tired or something?" He just carried on, totally ignoring my suggestion.

"I didn't want her to know yet, and you go along and tell her! Without mine or Izzy's permission!" He seemed to be getting angrier by the second, becoming restless. I still didn't know what I'd done wrong.

"Umm, Phineas? A-are you okay?" I tried calming him down, really carefully. Everyone knows that an angry Phineas is not a good Phineas.

"NO! I KNOW WHAT YOU'VE BEEN DOING! YOU'RE TRYING TO TAKE ISABELLA!" I must've jumped back about four feet from that shout. He was being completely irrational, and I wanted to get to the bottom of it before he really went off.

"Phin! Stop shouting! You're just going to make it worse!" What he would make worse, I didn't quite know, but I wanna be there for my brother. Tears began to stream down his cheeks and his voice became hoarse.

"I-I...I...love her. I LOVE HER! OKAY!? SHE CHOSE ME! DON'T TAKE HER AWAY!" His body was racking from the sobs he was emitting. I tried to move closer, but he just waved me away, yelling "GET LOST!" before running up to our room.

* * *

**Phineas' POV**

My head was spinning as I ran up the stairs. Why did Ferb, why? Why was he trying to take Izzy? "Aargh!" I screamed into my pillow. I thought about staying here for the night, but decided against it, packing an overnight bag. I grabbed it violently, then sprinted off back down the stairs. I ran so fast past Ferb that he was only a green haired blur. When I was out of the door, I just kept running. Where I was going to go was unclear to me, but the one place I could think of was the only place I wanted to go. Isabella's.

* * *

**Isabella's POV**

I was in my PJ's and half asleep when the doorbell rang. Phineas stood there, teary-eyed and tired. The moment I opened the door, he pulled me into a hug, murmuring into my hair, "...Can I stay the night...?".

"Oh, Phineas. I love you." I kissed him passionately and pulled him inside.

* * *

**So there it is, chapter 2! I hope you liked it, again, big thanks to, err, their name's up the top⬆⬆⬆(you can't miss it). Chapter 3 will be out ASAP, but, as I said last chapter, I am quite busy, so yeah. Hope you enjoyed, reviews are much appriciated , negative or positive (though I prefer positive, personally) but anyway, see you in the next chapter! Happy Fictioning!**


	3. Ch 3 A Friendship Divided

**Heyyy guys! Here's the third chapter, waiting for you in its unread glory. So, a guy named Phineas A, asked me how old Mr Phineas Flynn was. I guess it'd probably be easier to say everyone's ages, sooo, here you go! **

**Phin-21; Izzy-20 1/2; Ferb-22; Cadence-26; Jeremy-27; Baljeet-20; Buford-21; Fireside girls-ranged 19 to 21; Linda-52; Lawrence-55; Mrs Garcia-Shapiro-53**

**There we are, should make a bit more sense now. So, as always...Disclaimer: I do not own Phineas and Ferb, or any of the Canon characters. Enjoy and Happy Fictioning!**

**Chapter 3: A Friendship Divided **

**Author's POV**

Phineas and Isabella had slept soundly that night, waking up to hugs and snuggles, only to lull each other back to the black oblivion of sleep. Eventually, at around 10 am, Phineas decided that it would be a good idea to go back to his house and show everyone they weren't dead.

"Phin?"

"Yeah Izzy?"

"Do you love me?" She looked up at Phineas, who was in the middle of making a pot of coffee for them both. He paused for a moment, seeming to drift into a trance, then answered:

"Yes, yes I do. Why'd you ask?"

"I..I don't really know, I guess I'm just scared that..."

"Izzy," He cupped her face in his rough hands. "Don't be scared. Let me show you, if you're in doubt..."

"Phin...I-I don't know if-" He cut her off with his soft lips on hers, closing the gap between them. Isabella's eyes widened in shock - he was never so protective, not that she didn't like it, of course, but it still surprised her. She quickly relaxed though, enjoying the time that they shared. It was just theirs, and no-one else's.

When they had finally pulled apart, gasping for air, Isabella noticed the time.

"Oh crap! It's half ten! I have a meeting in half an hour! I gotta go and get dressed! Phin, you'll be late for-" He cut her of with a finger to her lips.

"It's ok. Let them wait. Take your time. With me, of course." Isabella giggled at that statement.

"Alright, _Sir _Phin. If you say so..." They both raced to Izzy's room, giggling manically.

* * *

_{Flashback} Last night, 8 pm_

_Phineas and Isabella were at a park outside an extremely tall, Ferb's-head-shaped block of flats. You could admit, it wasn't the best view, but after living in Danville for most of their lives, the newly-found couple didn't think twice about that matter. Funnily enough, the top flat (and the biggest) belonged to a certain Heinz Doofinshmirtz. Infamous for his wild, wacky, and failing inventions, he was determined not to let his latest one slide. With a surprised 'Perry the Platypus?!' Doof's and Agent P's fight began._

_-Doofinshmirtz's flat-_

_"Agent P?! You disguised yourself again?! Gee, I really need to start to recognise his traits more...Anyway, that's not the point! You ain't getting at my Suspectinator2000-inator! It's planned to fire at my brother, Roger, President of the Tri-State Area, and make him suspect everyone at his new speech for plotting against him! Ingenious, right?" Perry the Platypus had already fallen asleep on the dark purple, brick and plaster floor, letting out little snores every other moment or so. "P-Perry the Platypus?! Seriously? You aren't even going to listen to my evil rant today?! Oh my godd, talk about rude! Show your nemesis some respect, and get out here and fight like a real platypus!" With a swift kick to the face, Doof was already stumbling back a considerable few feet. "THAT'S more like it! COME AT ME!" The two were left battling in a blur of 'Ow!'s, kicks, punches and 'Grrrrrkkkkk!'s, striving for their goal, the answer obvious._

_-Central Park- _

_"Are...those people fighting?" Isabella asked Phineas, staring up at him with her brilliant blue eyes._

_Phineas rubbed his neck, his cheeks turning a faint pink. Boy, those eyes made his heart skyrocket. "Umm, I-I think so- Wait, what's that? It's like a laser beam- AAAGGHH!"__Phineas grabbed Isabella, pulling her close to him, before being coated in a bright purple light. Suspicion flooded over him and Isabella, and a feeling of protection flooded over them._

_{End of flashback}_

* * *

The gate to the Flynn-Fletcher backyard slowly swung open, to reveal a tall, redhead young man, standing next to a slightly smaller, ebony haired young woman, their hands entwined. At this sight, everyone, who were previously hard at work, stopped to stare at the latest attraction. The boys stood there with wide eyes, whilst the girls swooned affectionately. The couple parted to go and join their 'gender groups'.

* * *

**Phineas' POV**

"Wow, Phin. Good job you've done there, your girl sure is hot!" Buford stated.

"Hey," I replied, a bitter tone in my voice. "Why don't you stay away from my 'hot girl' and keep your comments to yourself?" My ginger eyebrows furrowed into a suspicious frown, as I bore my eyes into his. He lifted his palms up in surrender, slowly backing away. I felt my insides bubble up with anger, advancing on him as he touched Izzy's shoulder. She yanked it away, a look of disgust on her face. That was when I snapped.

"Buford..." I said quietly, staring directly into his eyes, my blue ones sparkling with anger. He turned, and almost whispered.

"Y-yeah?"

"Get off my property."

"Phineas, that's-"

"GO! GET OFF OF MY PROPERTY!" He opened his mouth to protest, but I interrupted him abruptly with a sharp shout. "_Now._" He sprinted out of the gate, not looking back once. Baljeet decided to stand up for his bully-friend-thing, despite the fact he was two years younger than me, and a foot shorter than me.

"What was that for? Huh? Why did you go off on one like that? Seriously!" We were now stood nose to nose (or as close as you can get it) and staring each other out.

"Baljeet...why don't you just go ahead and leave if you're so touched? It's not like we're going to be much use to each other? Is it?" He said nothing, and only stomped out of the backyard, a frown plastered to his face. I turned around, only to face Ferb, this time really nose to nose. Him being a whole year older than me - and naturally much taller - he was very scary when he was angry. He looked me very directly in the eyes - scarlet on blue. He then spoke the most and loudest I'd ever heard him speak in a row before.

"Phineas FLYNN! How DARE you! I, as your older brother, am DISGRACED! GET OUT! I'M SICK OF YOU!" He pointed towards the gate, hatred swimming in his expression. "GoodBYE, Phineas." I trudged out of the gate, Isabella running after me and grabbing my hand. I kissed her passionately, and we ran across the street into her house .

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**Sooo, here you go! Sorry if its not the best I could've done, but I have serious writer's block right now. Thanks for all the reviews, they are much appreciated! I hope to upload another chapter ASAP, but I'm pretty busy, anyway, I'll try. No idea what else to say in this, but...Happy Fictioning, and I'm gonna go eat!**


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